put text in a selecting state

var targetSelector = "<TODO: REPLACE SELECTOR>";

/* --------- Anything below this does not need to be changed. ---------- */
var targetElement = document.querySelector(targetSelector);

if (!targetElement) {
  throw new Error("Element not found");
}

/* Select the text of an element */
selectRange(targetElement, 0, targetElement.textContent.length);

function selectRange(element, startAt, endAt) {
  var selection = window.getSelection();
  var range = document.createRange();
  var textNode = element.childNodes[0];
  
  range.setStart(textNode, startAt);
  range.setEnd(textNode, endAt);
  
  if (selection.rangeCount > 0) {
    selection.removeAllRanges();
  }
  selection.addRange(range);
}